best environmental management practice in the...

Best practice 5.5 – Optimised large-scale or outsourced laundry operations

Best Environmental Management Practice in THE TOURISM SECTOR

Optimised large-scale or outsourced laundry operations

This best practice is an extract from the report Best Environmental

Management Practice in the Tourism Sector.

Find out about other best practices at www.takeagreenstep.eu/BEMP or download the full report at http://susproc.jrc.ec.europa.eu/activities/emas/documents/TourismBEMP.pdf

5.5

http://www.takeagreenstep.eu/BEMP

http://susproc.jrc.ec.europa.eu/activities/emas/documents/TourismBEMP.pdf


Best Environmental Management Practise in the Tourism Sector 2

5 5.5 Optimised large-scale or outsourced laundry operations

Description

Large-scale professional laundry operators can provide a more efficient alternative to on-site laundry

operations. Efficient large-scale and commercial laundry operations with a capacity of hundreds to

thousands of tonnes of laundry textiles per year typically achieve water use efficiencies of 5 to 6 litres

of water per kg of linen, compared with in excess of 20 litres per kg for non-optimised small-scale

laundry operations (Bobák et al., 2010; ITP, 2008). Specific water consumption as low as 2 litres per

kg has been demonstrated following process optimisation and water recycling (EC, 2007). It is

common for hotels and other tourism service providers, including restaurants, to outsource laundry

operations. This technique applies directly to all tourism service providers who control large-scale on-

site laundry operations (typically large hotels with over 500 rooms), and also to outsourced providers

of laundry operations. Tourism service providers can reduce their indirect environmental impact by

ensuring that their laundry providers implement best practice according to this technique.

Best practice for large hotels (over 500 rooms) and outsourced laundry providers is to operate

continuous batch washers (CBW) with counter-flow current, such as shown in Figure 5.23. Such

washers are efficient at laundry loads of over 250 kg per hour (Carbon Trust, 2009). Discrete batches

of 25 – 100 kg are introduced into one end of the machine and moved through a long 1 – 2 m diameter

drum 'tunnel' divided into water compartments with different quantities of water, and varying

temperatures and chemistry, by the motion of a water-permeable Archimedes screw. Such systems are

highly water efficient because clean water is only injected at the final neutralisation and rinse phases

of the cycle, and moves counter to the laundry movement, towards the wash and prewash phases,

where detergents are added, thus effectively recycling water through phases of progressively more

dirty laundry. In addition, water extracted from washed laundry during pressing and from the rinse

phase may be re-injected at the prewash and wash phases, and water from the wash phase may be

filtered and re-injected at the prewash phase, enabling water use efficiencies of better than 5 litres per

kg textiles.

Source: Girbau (2009).

Figure 5.23: An example of a 10 module continuous batch washer with counter-flow water current and

steam heating

The choice and dosing of laundry detergents has important implications for the quality of waste water

arising from laundry operations in terms of toxicity and eutrophication potential. There may be a

trade-off between waste water quality and process efficiency, as strong chemical action may reduce

the need for heating. In the US there is a move towards the use of ozone generators that inject ozone,

Best practice 5.5 – Optimised large scale or outsourced laundry operations


a powerful oxidising agent, directly into the rinse water as a highly effective disinfectant (US EPA,

1999). Benefits claimed for ozone injection include lower detergent dosing, lower temperature washes

and the avoidance of chemical additives for disinfection such as hydrogen peroxide (Cardis et al.,

2007). However, it is difficult to control ozone concentrations in order to guarantee disinfection and

realise these potential benefits (DTC LTC, 2011). Best practice is therefore to minimise chemical

dosing through process optimisation (e.g. water use minimisation and rinse water reuse), accurate

dosing, the avoidance of environmentally harmful chemicals such as hypochlorite and the selection of

more environmentally benign chemicals.

CBWs do not spin dry laundry as per washer-extractors. Following washing, drying is a two-stage

process based on:

mechanical dewatering – a quick process applied to all laundry exiting the CBW, usually using

a mechanical 'hydro-extraction' or 'membrane' press to remove most of the excess water, with

an energy demand in the region of 0.05 kWh per kg textiles;

thermal drying – a slower and energy-intensive process using heat to evaporate residual water,

with an energy demand of up to 1.4 kWh per kg textiles. Textiles are dried in tumble driers,

roller-ironers (flatwork), and finishers (garments).

Laundries are large consumers of energy, although this consumption represents a smaller fraction of a

typical guest 'footprint' compared with laundry water consumption (Figure 5.3 in section 5). In large

laundries, steam is often used as a convenient energy carrier to heat all major processes, from the

prewash phase of the CBW process, through drying, to ironing or finishing. Bobák et al. (2011)

compare an 'average' steam-heated laundry with poor energy management with an optimised steam-

heated laundry (Figure 5.24). Typically, steam is generated in gas boilers, and heat losses occur at this

stage, and during distribution via the walls of transfer pipes, and through leaks. This can offset some

of the efficiency advantages, such as use of efficient CBWs, of large-scale laundries.

In a large laundry, the first phase of thermal drying is performed by gas- or steam-heated tumble

driers, and can require approximately 0.4 kWh per kg textiles – a similar amount of energy to that

consumed in the CBW (Figure 5.24). The second phase of thermal drying is performed by roller

ironers for damp flatwork (e.g. bedclothes) or a tunnel finisher for damp garments. In finishing

tunnels, garments are first subjected to a steam spray to de-wrinkle them, a hot damp downward blast

of air to straighten them, and a hot dry blast of air to remove moisture.



Table 5.23: Portfolio of best practice measures for large-scale laundry operations

Stage Measure Description

House-

keeping

Reduce volume of

laundry generated Encourage guests to reuse towels and bed linen

(section 5.3).

Minimise use of tablecloths and napkins in

restaurants.

Washing Optimisation of

continuous batch

washers

Match water input to batch washing requirements

and optimise water cycling through the process to

achieve correct water levels and liquor ratios.

Monitor and adjust machinery and dosing to

minimise textile wear (Hohenstein Institute, 2010).

Water recycling In addition to recovery of rinse and press water,

wash water may be recycled through a micro-filter

system to re-inject into the prewash.

Heat recovery Recover heat from steam used in the drying process

and waste water to heat incoming fresh water.

Green procurement

of detergent and

efficient dosing

Use laundry detergents compliant with Nordic Swan

criteria for laundry detergents for professional use

(Nordic Ecolabelling, 2009).

Match detergent dosing to recommendations and

laundry batch requirements.

Optimise with water level and temperature, and

mechanical washing effectiveness. Soften hard

water.

Drying Optimal use Maximise mechanical drying according to textile

type, fully load dryers, and control drying times to

terminate at equilibrium moisture content (~ 8 %).

Maintenance Ensure adequate dryer insulation, check for leaks,

moisture sensor operation, duct blockages, and clean

lint from filters every hour (or install automated lint

cleaner).

Finishing Ironer type Replace old ironers with efficient new ironers (e.g.

heating band design) of appropriate width for

bedclothes, and ensure adequate insulation and

maintenance to avoid steam leaks.

Optimal loading Install semi-automatic loader, adjust roller timing to

achieve final textile moisture content in equilibrium

with atmospheric conditions after single pass.

Minimise energy use

in tunnel finishers Minimise heating time for textiles to reach

maximum drying temperature, and decrease

temperatures in subsequent zones to maintain this

temperature. Recirculate hot air and ensure adequate

insulation of tunnel. Aim for final textile moisture

content in equilibrium with atmospheric conditions.

Minimise chemical

use for finishing Avoid, or if not possible, minimise, the use of water-

and dirt-repellent chemicals.

Entire

process

Optimisation

through water and

heat recovery, and

maintenance

Optimise the entire laundry process. Recover heat

from flue-gas to heat steam feeder water, recover

heat from dryer/ironer steam and waste water to heat

CBW inflow. Ensure entire distribution network is

insulated, inspected and maintained to prevent leaks

(install automatic leak detection system).



Achieved environmental benefit Table 5.24 summarises energy and water savings that can be achieved in washing drying processes.

Ensuring correct water levels in each CBW compartment alone can reduce water consumption by

30 % (Carbon Trust, 2009). Optimisation of an older CBW can reduce water consumption by 50 %

and energy consumption by 70 % according to P&G (2011). Bobák et al. (2011) estimate that

optimisation of a steam laundry system can reduce total energy use by 60 %, or 1.45 kWh per kg

textiles (Figure 5.24), after implementation of various water reuse and heat recovery steps.

Table 5.24: Energy and water savings achievable from various measures to improve laundry efficiency

Measure Saving

Replace washer-extractors with a CBW 50 % reduction in energy and water consumption

(Carbon Trust, 2009)

Fine-tune CBW 30 % reduction in water consumption (Carbon Trust,

2009)

Reduce wash temperature from 80 ºC to

60 ºC 25 % reduction in CBW energy consumption

Reuse of dewatering press and rinse water

in prewash compartment 2 – 3 L per kg textile (EC, 2007)

Waste water heat recovery 5 – 10 % heating energy (Carbon Trust, 2009)

Microfiltration and reuse of process wash

water

Up to 75 % reduction in water consumption and

25 % reduction in energy (Wientjens B.V., 2010). 2

L per kg textiles (EC, 2007).

Use of low pressure steam from

condensate to heat rinse water

10 % reduction in total energy consumption (Carbon

Trust, 2009)

Maximise mechanical dewatering 5 % reduction in total energy consumption(*)

Recycle tumble-dryer heat with heat

exchanger

Up to 35 % reduction in drying energy (Jensen,

2011)

Optimise drying 0.23 kWh per kg textiles, 9 % total energy use

(Bobák et al., 2011)

Optimise ironing 0.31 kWh per kg textiles, 13 % total energy use

(Bobák et al., 2011)

Optimise entire system 60 % reduction in energy consumption (Bobák et al.,

2011)

(*)Achieve 50 % instead of 58 % residual moisture content.

Microfiltration of CBW process water and reinjection into the prewash phase can reduce net specific

water consumption by 2 L per kg textiles (EC, 2007). Maximum water savings of 75 % and maximum

energy savings of 25 % are claimed for CBW water recycling systems incorporating microfiltration

(Wientjens B.V., 2010).



Source: Based on data in Bobák et al. (2011).

Figure 5.24: Energy use for an average and an optimised continuous batch washer system based on use

of steam generated by natural gas

Appropriate selection and dosing of detergent and conditioning chemicals reduces COD loading to the

sewer (and, depending on the final waste water treatment effectiveness, to the environment), and

reduces water toxicity. In particular, avoidance of hypochlorite avoids emissions of toxic and bio-

accumulating absorbable organic halide (AOX) compounds.

Appropriate environmental indicator

Benchmarks of excellence

Nordic Ecolabelling (2010) present criteria for awarding points to textile service providers, according

to environmental performance for the laundering of different textile categories. To date, 31 laundry

sites in Norway, 16 in Sweden, and one in Finland have been awarded the Nordic Swan ecolabel.

Accordingly, the following overarching benchmark of excellence is proposed.

BM: all laundry is outsourced to a provider who has been awarded an ISO type-1 ecolabel

(e.g. Nordic Ecolabelling, 2010), and all in-house large-scale laundry operations, or

laundry operations outsourced to service providers not certified with an ISO Type-1

ecolabel, shall comply with the specific benchmarks for large-scale laundries

described in this document.

Water

Nordic Ecolabelling energy and water efficiency criteria for the award of maximum points for the

textile categories 'hotels' and 'restaurants' are proposed as the basis of benchmarks of excellence.

These benchmarks correspond with state-of-the-art performance identified by the Hohenstein Institute

(2010) from data relating to over 1.7 million washes in commercial laundries.

0.0

0.5

1.0

1.5

2.0

2.5

AVERAGE OPTIMISED

En

erg

y c

on

su

mp

tio

n (

kw

h /

kg

te

xtile

s)

.

Finishing

Ironing

Drying

CBW

Losses



The appropriate environmental indicator for laundry water efficiency is litres of water per kg laundry

and the proposed benchmark of excellence for large hotels, and outsourced laundry providers for

accommodation and restaurants, is:

BM: total water consumption over the complete wash cycle ≤5 L per kg textile for

accommodation laundry and ≤9 L per kg textile for restaurant laundry.

Energy

The appropriate environmental indicator for laundry energy efficiency is kWh per kg dried, finished

laundry, and the proposed benchmark of excellence for large hotels and outsourced laundry providers

is:

BM: total process energy consumption for dried and finished laundry products ≤0.90 kWh

per kg textile for accommodation laundry and ≤1.45 kWh per kg textile for

restaurant laundry.

Chemicals

Proposed benchmarks of excellence for chemical use are:

BM: exclusive use of laundry detergents compliant with Nordic Swan ecolabel criteria for

professional use (Nordic Ecolabelling, 2009), applied in appropriate doses.

BM: waste water is treated in a biological waste water treatment plant having a feed-to-

microorganism ratio of <0.15 kg BOD5 per kg dry matter per day.

Cross-media effects Optimised CBW processes enables highly efficient use of water, energy and washing detergents, with

no major cross-media effects.

Where accommodation or food and drink providers outsource laundry, the improved efficiency of

laundry operations in terms of water, energy, and chemical consumption achievable in an optimised

large-scale laundry outweigh the energy consumption and air emissions associated with laundry

transport. Transporting 500 kg of laundry a total distance of 30 km (return trip) in a small commercial

van would consume approximately 0.042 kWh of diesel per kg laundry1, compared with possible

energy savings in the region of 0.5 – 1.0 kWh per kg laundry arising from processing in an optimised

large-scale laundry.

The energy requirements for microfiltration of process water, at approximately 0.75 kWh energy per

m3 recycled (Wientjens B.V., 2010), are small compared with heat recovered in recycled water (1.16

kWh per m3 per degree centigrade of heat recovered).

1 Assuming diesel consumption of 7 L/100 km



Operational data Transport

Transport of outsourced laundry should be optimised by the laundry service providers based on the

distribution of clients, timing of collection and deliveries in relation to traffic, backhauling

(combining delivery and collection), and the size, efficiency and EURO rating of delivery vehicles.

CBW design

Table 5.25 presents some important features of CBW systems that contribute towards optimum wash

performance. Newer designs of CBW have rotating perforated drums with smooth walls in place of

the original basic Archimedes screw design, resulting in improved mechanical wash action and

reduced abrasion and blockages. New designs enable full rotation and free-fall of laundry, maximising

laundry flow-through and compression whilst minimising abrasive rubbing (EC, 2007).

Table 5.25: Features of CBW systems to optimise performance across the four main factors affecting

wash effectiveness

Mechanical action Chemical action Temperature Time

Straight drum walls

Large drum diameter

Programmable g-

force factor

Weight dependent

doings

Water level and rinse

water

No drum core

60mm foamed drum

insulation

Temperature control

for disinfection

Waste water heat

exchange

Quick drain

Quick heating

Optimised cycle time

Source: Derived from EC (2007).

Batch organisation and loading

Loading rates of CBWs are strongly and inversely related to the specific efficiency, even though some

new machines adjust programme water consumption and chemical dosing according to load weight.

Where loads are deposited into the CBW via a monorail system, classification bags in the sorting area

may be attached via weighing devices that automatically send the bag forward once the correct load

weight is achieved. The accuracy of this process should be checked by operatives, facilitated by

clearly marking the correct load position on the weighing scales (Carbon Trust, 2009).

For hotel laundries with CBW machines, it is important to sort batches according to textile type and

degree of soiling (see Table 5.19 and Table 5.20 in section 5.4). For commercial laundries, it can be

more efficient to spread laundry from different customers across batches to maximise CBW loading

rates, and separate afterwards. Some commercial laundries rent textiles to clients, such as hotels and

hostels, in which case laundry may not need to be separated by the customer.

Water and energy optimisation in CBW

Water and energy use efficiency in the CBW are strongly related, and optimisation is bound within

laundry washing effectiveness and hygiene parameters. As a general rule for CBW, the conductivity

difference between clean water and final rinse water at the end of the rinsing zone should be less than

0.3 mS/cm (above 0.5 mS represents a potential threat to human health) (Proctor and Gamble, 2011).

Full drainage of wash water before laundry is transferred to the rinse compartment reduces soiling of

rinse water, and thus the quantity of water required in rinse compartments. There are numerous

opportunities for water recycling to optimise water use efficiency in a CBW, as indicated in Figure

5.25. Final rinse water extracted by mechanical pressing can be reused directly for the prewash, along

with water reclaimed from the start of the rinse phase, to save a total of 2 – 3 litres per kg textile (EC,

2007).



Source: EC (2007).

Figure 5.25: Optimised water reuse and heat recovery for a 14-compartament CBW

In addition, microfiltration of used wash water through ceramic filters or similar (Figure 5.26) can

enable up to 75 % of effluent water and 25 % of energy (in warm water) to be reused (Wientjens B.V.,

2010). As an example, the AquaMiser system is compact, weighing 175 kg and fitting within 2m2, has

a max output capacity of 6m3/hr filtrate, operating at 4.5 kW using 500 litres (N) compressed air per

hour at 6 – 8 bars pressure, and has a backwash filter control to minimise maintenance requirements

(Wientjens B.V., 2010). The achievable water recycling rate is lower for optimised CBW systems

already operating with efficient water cycling. Water use as low as 2 L / kg textiles is reported (EC,

2007).

0.75

micron

filter

0.25

micron

filter

BackwashSEWER

PU

MP

PU

MP

Figure 5.26: Water recycling using micro-filtration

Using heat recovery to heat incoming freshwater at the final rinse phase has the advantage of

increasing the final temperature of the textiles and thus reducing drying energy requirements.

Pump synchronised

with rinse flow

Wastewater to

drain

Freshwater

Heat exchanger

Press

Freshwater to

rinse



However, rinse water that is recycled to the prewash compartment should not be above 40 ºC

otherwise it could fix stains such as blood into textiles. There is some scope to reduce wash

temperatures for hospitality laundry that is typically lightly soiled (see Table 5.20 in section 5.4).

Laundry disinfection requirements vary across EU Member States. In the UK, high temperature

disinfection is not required (but is recommended) for hospitality laundry (Carbon Trust, 2009).

Certification standards based on hygiene testing, such as the German RAL-GZ 992/1 standard, may

be used to verify hygiene performance.

CBW optimisation should be performed by qualified laundry technicians or consultants. Once

programmes have been pre-set, they should not be changed by laundry operatives, and it is imperative

that operatives use the correct preset programmes – this should be clearly guided by charts visible at

the point of use.

Chemical use

Following dirt removal, hydrogen peroxide is an effective oxidising agent to kill bacteria and viruses.

For hospitality laundry that does not require sterilisation, hypochlorite is not necessary

(Bundesanzeiger Verlagsgesellschaft, 2002). If stubborn stains remain after washing, hypochlorite

may be added selectively at the rinse stage. Hydrogen peroxide may be substituted with ozone

generators that directly inject ozone into cool rinse water, to attain a concentration of 1.5 to 3.0 mg/l

O3 that kills bacteria and viruses at low temperature (US EPA, 1999). However, it is difficult to verify

O3 concentrations in the rinse water, and this technique is rarely applied in Europe.

Typically, approximately 10 g of detergent is used per kg laundry in a CBW (EC, 2007), with

auxiliary chemicals such as peracetic acid (PAA), hydrogen peroxide, chlorine, acid and fungicide.

EC (2007) refer to Sanoxy detergent that reduces water and total energy consumption… The chemical

and energy cost implications of lower wash temperatures are described under 'Economics', below.

Mechanical dewatering

Depending on the type of textile, the mass of water contained in the saturated fabric immediately after

washing can be two to three times the mass of the dry fabric. Thermal drying is an energy-intensive

and relatively time-consuming process that can use over 1 kWh per kg textiles. Considerable energy

savings can be achieved by maximising the use of quick and efficient mechanical dewatering (Figure

5.27), using either a dewatering press or a centrifuge. Theoretical energy consumption for a

commercial water extraction press with a load capacity of 50 kg is 0.035 kWh/kg textile (dry).

Maximising mechanical dewatering can also reduce water consumption by providing more water that

can be recycled into the wash process (see Figure 5.23). The effectiveness of mechanical dewatering

depends on: (i) pressing time; (ii) temperature of the rinse water; (iii) pressure; (iv) textile type.



Figure 5.27: The relative time and energy consumption required for mechanical dewatering and thermal

drying of textiles

Table 5.26 shows the sensitivity of residual moisture content to key parameters. Optimisation of the

drying process depends on the type of textile (e.g. maximum pressure constraints) and integration

with the wash process. Increasing the final rinse temperature from 25°C to 55°C can reduce residual

moisture content after pressing by 8 %, reducing drying energy requirements. This is an important

consideration when calculating the payback of waste heat recovery in incoming rinse water. Timing

should be set to achieve maximum drying within the time available between CBW batch deliveries.

Table 5.26: Residual moisture contents after press dewatering under varying conditions

Key variable Conditions Moisture

content

Time (cotton @ 51 bar) 90 seconds 53 %

180 seconds 43 %

Temperature (cotton @ 51 bar

and 90 seconds)

25 ºC 58 %

55 ºC 50 %

Pressure (cotton @ 50 ºC, 90

seconds)

28 bar 64 %

51 bar 53 %

Textile (@ 25 ºC, 51 bar) Cotton 58 %

Polyester/cotton (65/35) 41 %

Source: EC (2007).

Moisture contents following dewatering should not exceed 50 % for sheets and 52 % for towels to

ensure efficient drying in ironers and tumble-dryers, respectively (Carbon Trust, 2009). High moisture

contents may indicate a hydraulic leak or faulty pump in the press system that requires maintenance or

replacement, and can be identified through periodic weighing of laundry items.

Thermal drying

Following mechanical dewatering, towels and bath mats are dried in tumble driers, sheets, tablecloths

and napkins can be transferred directly to dewatering ironers, and garments are dried in finishers.

According to EC (2007), thermal drying options in large-scale laundries can be ordered according to

300%

100%

200%

0%


(0.14 kWh/kg)

Thermal drying

(0.42-1.40 kWh/kg)

Time

Time

MC (%)


(~0.05 kWh/kg)

Thermal drying

(~0.5 kWh/kg)



energy efficiency accordingly (kg steam required to remove one litre of water from textiles in

brackets):

old, poorly insulated ironer (2.5)

steam tumble-dryer (2.0)

new ironer (1.6)

garment finisher (1.0).

Optimisation of the thermal drying process should be based on maximisation of the lowest energy

processes available and applicable to the fabrics being laundered. Old ironers should be replaced by

efficient ones as soon as is economic (see Table 5.28), and use of tumble-dryersshould be minimised.

Over drying should be avoided by calculating drying times to ensure that the final moisture content

after the last drying process is as close as possible to the equilibrium moisture content of the textile

under standard atmospheric conditions (e.g. 6 – 8 % moisture for cotton).

Large steam tumble driers require approximately 0.5 kWh per kg textiles (Figure 5.24). Measures to

reduce energy consumption during drying are to recycle hot process air, rapid initial heating of the air

to minimise textile heat-up time, optimum drum loading to ensure textile movement and good heat

transfer, regular filter cleaning (once per hour), and optimisation of end-point textile moisture content

in relation to any further drying in the ironing or finishing phase and according to a target textile

moisture content in equilibrium with atmospheric conditions. End-of-cycle terminators based on

infrared detectors that leave 8 % moisture in towels are optimum and can be easily retrofitted. Tumble

driers with axial, rather than radial, flow have been demonstrated to use significantly less energy

(Carbon Trust, 2009).

Monthly inspections should be performed to check that heated air is not bypassing the rotating cage,

that the door seal is sound, that there are not any air leaks, and that melted plastic or other

contamination is cleared from the cage. Automatic lint screen cleaning systems can be installed to

maintain optimum operating efficiency.

For dryers and finishers, direct gas heating is more efficient than indirect heating via steam owing to

the energy losses through heat exchange and distribution for high-energy-state steam (Figure 5.28).

The ratio of useful heat energy output to energy input is typically 0.85 for direct gas-fired systems

compared with 0.7 for steam systems. Gas-fired tumble driers may be up to 30 % more efficient than

steam-heated driers (Carbon Trust, 2009). Nonetheless, steam provides a convenient centralised

source of heating for large laundries processing more than 500 kg textiles per day (EC, 2007). Steam

leakage can be minimised by installation of automated steam trap leakage detection systems, and

systems can also be optimised with respect to the entire laundry process (Figure 5.30), which can

reduce losses associated with steam generation and distribution by 90 %, to just 0.05 kWh/kg textiles

(Bobák et al., 2011).



Source: EC (2007).

Figure 5.28: Energy consumption for sheet fabric (ironer) and garments (finisher) based on direct gas

heating and indirect heating using steam

The majority of laundry from the hospitality sector is flatwork that will require ironing rather than

finishing (for garments). Where mechanical water extraction brings moisture content down to 50 % or

less, flatwork may be transferred directly to roller ironers, by-passing tumble driers. Large-scale

laundry dewatering irons apply pressure and heat to reduce residual moisture content in flatwork

textiles (e.g. bed linen and tablecloths), and are usually based on a two or three-roller design (Figure

5.29). The efficiency of large-scale dewatering ironers has improved considerably in recent years,

from consumption of 2.5 kg of steam per litre of water removed to 1.6 kg steam per litre of water

removed from the textiles (EC, 2007) – these values translate to specific drying energy requirements

of 0.6 and 0.4 kWh per kg textiles at 50 % moisture content, respectively. One feature of more

efficient ironers is heat-retaining hoods. The efficiency of roller ironers should be monitored, and the

machinery frequently inspected, to identify maintenance actions. For example, roller padding can

become worn, reducing contact pressure with the textiles and thus drying efficiency. Carbon Trust

(2009) recommend replacing the three layers of thin material traditionally used as roll padding with

two layers of stronger polyester needle-felt to improve ironing performance by up to 30 %, and reduce

energy consumption.

Source: Elaborated from carbon Trust (2009).

Figure 5.29: Schematic representation of rigid-chest three-roll ironer operation

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Ironer Finisher Ironer Finisher

GAS STEAM

Specific

energ

y u

se (

kW

h/k

g textile

) Wash Tumble drying

Ironing Finisher



A derivative of the traditional rigid chest roller ironer shown in Figure 5.29 is now being

commercially marketed as a more energy-efficient alternative. Heating band ironers use a heated sheet

of high quality stainless steel to maintain pressure against the rollers, enabling a higher pressure of up

to 16 bars to be applied evenly across textiles (Kannegiesser, 2004). It is claimed that heating bands

also offer continuous heating over their entire surface, including the 'bridge' between rollers, and

suffer less from the wear-induced contact area reduction that occurs when the padding on

conventional roller systems is worn (Kannegiesser, 2004; EC, 2007). Table 5.27 presents operational

data for a modern heating-band ironer compared with a traditional rigid chest ironer. For the heating-

band ironer, a 90 % decrease in heated mass reduces start-up heating by 189 kWh per day, and the

reduced radiation losses from the smaller heated-surface area reduces heating by 120 kWh per day.

Table 5.27: An example of typical daily energy losses for a rigid-chest ironer and a heating-band ironer

of the same capacity, both heated by steam

Rigid chest ironer Heating band ironer

Specifications 1200 mm diameter, 3500 mm

width, 3 rolls, 6 tonnes heated

steel

1200 mm diameter, 3500 mm

width, 2 rolls, 0.62 tonnes heated

steel

Steel heating-up (daily) 211 kWh / day 22 kWh / day

Radiation 192 kWh / day 72 kWh / day

Escaping vapour 88 kWh / day 18 kWh / day

Total 491 kWh / day 112 kWh / day

Energy saving 379 kWh / day

NB Assumes one 8 hour per day shift and 1.83 kg steam = 1 kWh energy.

Source: EC (2007).

Energy consumption during ironing can be minimised by operating driers as close to rated capacity as

possible – this can be achieved by having a buffer stock of flatwork ready for ironing in case of any

interruptions in the line from previous processes. The most efficient loading systems are semi-

automated, comprising monorails to which the corners of textile sheets are clipped and that deposit

sheets onto the flatwork ironing surface automatically in response to a signal from a remote operative.

Automatic feeders should be adjusted to give edge to edge feeding in order to cover the width of the

iron, and roll-to-roll speed differentials set to give 50 mm stretch in 10 turns of an 800 mm diameter

roll (Carbon Trust, 2009). The roller speed should be adjusted to ensure that flatwork leaving the

ironer is dried to equilibrium moisture content in one pass, and that as much of the ironer surface as

possible is covered with flatwork at all times of operation.

In garment finishers, approximately one kg steam (0.55 kWh heat) is required per litre of water

evaporated from the textiles. The energy requirement of garment finishing is minimised by the

recirculation of 90 % of the air and optimisation of temperature distribution in the heating, finishing

and drying zones according to the textile density. The temperature of succeeding zones should

decrease to ensure rapid textile heat-up and maintain a constant textile temperature (EC, 2007).

Following ironing, textiles may be treated with chemicals to repel water and dirt. This is unnecessary,

especially for accommodation textiles that are frequently laundered, and should be avoided where

possible.

System optimisation

In relation to overall laundry system optimisation shown in Figure 5.30, the most important measures

to reduce heat losses from the steam system are given below.

Recovery of heat from the flue-gas to heat steam feeder water (point 1 in Figure 5.30).



Recovery of steam from the drying cycle, in an expander, to heat process water in the CBW

(point 2 in Figure 5.30). This can save around 10 % of entire laundry energy demand (Carbon

Trust, 2009).

Recovery of heat from waste water (ideally combined with water recovery) to heat incoming

process water to the CBW (point 3 in Figure 5.30). This can save 5 – 10 % of laundry heat

demand.

Regular inspection and maintenance of the distribution system to prevent leaks (point 4 in

Figure 5.30).

Appropriate insulation of pipes, CBW, dryers, finishers and irons to minimise heat losses (point

5 in Figure 5.30).

Source: Derived from Bobák et al. (2011).

Figure 5.30: Steam-heated laundry with optimised energy management

EC (2007) recommend corrugated pipe heat exchangers for their efficiency, robustness and tolerance

of soiled water, and specify the following check criteria to optimise the heat exchange process: (i) the

flow directions are connected in counter-current direction; (ii) there are turbulences in the liquids; (iii)

there is a large heat transfer surface; (iv) the mass flow and the temperature differences in both

directions are the same; (v) as much time as possible is provided for the heat exchange (i.e. for a

tunnel washer, throttle the rinse flow to almost the total cycle time).

The following sequence of checks may be useful to consider for optimisation of the entire laundry

process:

SYD = Steam dryer; IRO = Ironers; TUF = Tunnel finisher

1

2

3

4

5



1 Firstly, ensure that batch management is optimised to maximise CBW loading rates and that

the CBW is performing according to correctly specified programme parameters.

2

Based on typical batch characteristics, assess the potential to reduce wash temperature,

water use and chemical dosing. The potential for this may be high for typically lightly soiled

hotel laundry – it is worthwhile to experiment with different temperature and chemical

dosing settings. Aim for a rewash rate of 3 – 5 % (lower indicates over-washing, higher

indicates under-washing). Balance chemical costs against savings from reduced energy

consumption and textile wear (see 'Economics').

3

Minimise thermal drying requirements by maximising mechanical dewatering press times,

and optimise the efficiency of thermal drying by ensuring maximum loading rates in tumble-

dryers and flatwork ironers. Avoid over drying: control timing to achieve final moisture

contents of 8 %, in equilibrium with atmospheric conditions (install moisture sensors in

tumble driers).

4

Ensure that all economically viable water reuse opportunities are being exploited, especially

reuse of rinse water in earlier rinse of prewash compartments. Assess the economic viability

of installing a microfiltration system to reuse prewash water in the prewash or wash cycle.

Balance system modification costs against water, energy and chemical savings.

5

Ensure all economically viable heat recovery opportunities are being exploited. Heating

incoming final rinse water with waste water from the main wash is simple and cost effective,

but requires careful control: a higher rinse temperature reduces drying requirements, but

should not cause prewash temperature to exceed 40 ºC when reused (in order to avoid the

fixing of stains).

6

Inspect and test all equipment frequently, and perform regular maintenance, especially to

tumble driers (check filters, fans, ducts, moisture sensors) and roller-ironers (adjust speed

settings and check for padding wear).

7

Calculate when it would make financial sense to invest in new equipment, such as a new

CBW or heated-band ironer. More efficient drying equipment can pay back relatively

quickly: in particular mechanical dewaters and high-efficiency ironers. Assess the possibility

to use direct gas heating instead of steam heating.

Regular system maintenance is crucial to maintain optimal operating efficiency (Carbon Trust, 2009).

Equipment should be checked weekly, and in some cases daily, for problems. Regular maintenance

tasks include: (i) clearing wax from vacuum fans and ducts on the ironers; (ii) repairing holes in

grilles above the tumble dryer heater batteries to prevent lint blockage; (iii) adjusting hanger delivery

mechanisms at the tunnel finisher to give one garment per peg. Equipment tuning should be

performed every three months, including:

adjustment of 'wait' times in the hydro-extraction press programme to maximise press times;

adjustment of the roll-to-roll stretch on ironers to improve the heat transfer over the gap pieces

between the rolls;

adjustment of end-of-cycle terminators on tumble-dryers so that they leave 8 % moisture in

towels.

Realisation and maintenance of optimum efficiency requires monitoring and reporting of key

performance indicators for energy and water use efficiency: kWh energy and L water consumed per

kg laundry processed. These should be reported weekly or monthly in charts that enable easy tracking

of progress over time, and can be calculated from: (i) energy (electricity, gas, oil, steam) and water

bills; (ii) the number of pieces laundered. The average piece weight of mixed laundry items is around

0.5 kg (Carbon Trust, 2009), but this may vary for hospitality laundry and can be established for

individual laundries through weighing a sample of laundry items.



Applicability Optimised CBW laundry processes incorporating heat recovery and water recycling following

microfiltration are applicable to large hotels with over 500 rooms, and commercial laundries serving

the entire hospitality sector (accommodation, restaurants, bars, etc.).

Laundry from food preparation in restaurants and accommodation establishments is typically more

heavily soiled than laundry from rooms in accommodation, and requires more energy and water-

intensive laundering (see 'Environmental indicators' section above).

Economics Most best environmental management practice measures for large-scale laundries are based on water,

energy or chemical resource efficiency, and therefore have relatively short payback times when

implemented in new systems or following retrofitting. Table 5.28 summarises some important

economic factors for the referenced best practice measures.

Replacing older drying equipment such as irons with more efficient new models typically results in

large annual energy savings of tens of thousands of euro (Table 5.28). Thus, it can be financially

worthwhile to bring forward replacement of older equipment (e.g. after a major breakdown).

The installation of microfiltration equipment to filter prewash water for reuse offers an acceptable

payback time, in the region of two years, where water supply and disposal costs are at or above

EUR 2.00/m3.

Table 5.28: Important economic considerations associated with laundry best practice measures

Measure Economic considerations

CBW water and

energy

optimisation

At a water service (provision and treatment after disposal) price of EUR 2/m3 and

a gas price of EUR 14/GJ (EUR 3.89/MWh), optimisation of an older CBW

system processing 7 t/day of laundry can achieve annual cost savings of EUR

25 000 for water and EUR 40 000 for energy (P&G, 2011). These water and

energy savings equate to EUR 14 and EUR 24 per tonne of laundry processed,

respectively. This water saving cost would increase to EUR 21 per tonne of

laundry at a water service cost of EUR 3/m3. One company offers a CBW

optimisation service with payback periods as short as 12 months (P&G, 2011).

Laundry energy

optimisation

According Bobák et al. (2011), energy optimisation of the entire laundry process

can yield energy cost savings of EUR 73 per tonne laundry, of which EUR 35 per

tonne are attributable directly to the optimisation of drying processes.

Replacing an older ironer using 2.5 kg steam per litre of water removed with a

new ironer using 1.6 kg steam per litre of water removed will reduce annual

energy costs by EUR 27 000 for a laundry operating at 10 tonnes per day, five

days per week.

Water

filtration:

At a water service (provision and treatment after disposal) price of EUR 3/m3,

recycling of prewash water from a 12 t/day laundry CBW process through a

microfiltration system can save EUR 27 000 per year (EUR 9 per tonne laundry).

This compares with a capital and installation investment of EUR 40 000, thus

leading to a payback period of 17 months (EC, 2007). The payback time increases

to 21 months and 27 months at a water service price of EUR 2.50 and EUR 2.00

per m3, respectively.

Chemical

selection and

dosing

Chemical selection and dosing should be optimised with water, energy and textile

wear costs for different batch characteristics. Efficient dosing based on laundry

type and degree of soiling reduces costs.

Avoidance of more environmentally harmful chemicals can reduce costs, but

substitution with more environmentally friendly chemicals can increase costs.

Selection of ecolabelled detergents may increase detergent costs.



Textile wear represents a significant component of washing costs, and can account for half of washing

costs for relatively efficient operations using 6 L/kg laundry (left bars on Figure 5.31). Reducing

maximum wash temperature from 90 ºC to 50 ºC reduces textile wear by up to 50 %. Figure 5.31

highlights how the cost benefits of lower temperature washes are offset by chemical costs that can

increase by a factor of 1.8. The cost effect of temperature reduction is laundry-specific, and can be

positive or negative. For efficient laundries, a decisive factor is whether or not the laundry operators

bear the cost of textile wear. For in-house laundries on accommodation premises, reduced textile wear

costs can justify temperature reductions, whilst for outsourced laundries temperature reductions may

not be justified by cost savings that exclude textile wear.

NB: Water price 2 EUR/m3, steam price EUR 23.5/tonne (gas heating), chemical price ranging

from EUR 1 000 to EUR 1 800 per tonne, and textile price EUR 7 500 per tonne.

Source: Based on modified values from EC (2007).

Figure 5.31: Specific washing costs and textile wear for a 13-compartment CBW under high load rates

and 8-compartment CBW under low load rates, for higher and lower temperature washes

It is important to implement heat recovery after water optimisation, as the latter process can reduce

water consumption, and thus required heat-exchanger size, by approximately 30 %, reducing heat

exchanger installation cost by 15 % (Carbon Trust, 2009).

Driving force for implementation The main driving force for implementing optimised CBW processes is economics, as described above.

For large hotels, implementation of efficient laundry systems may also be driven by environmental

award schemes, or simply public relations benefits.

For commercial laundries, improved environmental performance, especially if recognised by third-

party certification, can improve business opportunities, especially with hospitality enterprises

operating green procurement policies.

0

50

100

150

200

250

90ºC 70ºC 85ºC 50ºC 50ºC

1241 kg/hr 222 kg/hr 346 kg/hr

EU

R /

to

nn

e la

un

dry

Textile wear

Water

Steam

Chemicals

Chemistry

optimised

~6 L/kg specific water

consumption

~20 L/kg specific

water consumption



Many tourist destinations, especially around the Mediterranean, suffer water stress during peak

season, and there is pressure to reduce water use associated with tourism. Economic driving forces

may be stronger in such destinations if authorities impose higher water charges.

References

Bundesanzeiger verlagsgesellschaft, Annex 55, Guidelines for the interpretation of Annex 55 to

the German Waste water Ordinance (requirements for waste water disposal from commercial

laundries), German Ministry of Environmental Protection, 13th March 2002, Bundesanzeiger

verlagsgesellschaft mbH, Köln.

Bobák, P., Pavlas, M., Kšenzuliak, V., Stehlík, P., Analysis of energy consumption in

professional laundry care process, Chemical Engineering Transactions, Vol. 21 (2010), pp.

109 – 114.

Bobák, P., Galcáková, A., Pavlas, M., Kšenzuliak, V., Computational approach for energy

intensity reduction of professional laundry care process, Chemical Engineering Transactions,

Vol. 25 (2011), pp. 147 – 152.

Carbon Trust, Energy saving opportunities in laundries: how to reduce the energy bill and the

carbon footprint of your laundry, Carbon Trust, 2009, London UK. CTV040.

DTC LTC, personal communication with DTC LTC laundry consultants UK, 16.08.2011.

EC, Regulation (EC) No 648/2004 of the European Parliament and of the Council of 31 March

2004 on detergents, OJEU, L104/1, Brussels.

EC, Training modules on the sustainability of industrial laundering processes, EC, 2007.

Available at: http://www.laundry-sustainability.eu/en/index.html

Girbau, TBS-50 batch washer, Girbau P00567 05/09, Girbau 2009, Barcelona

Henkel, Case study Persil Megaperls by Henkel AG and Co. KGAA Documentation. Case

Study undertaken within the PCF Pilot Project Germany, PCF Germany, 2009

Hohenstein Institute, Sonderveröffentlichung: zum 60 Geburtstag von Dr. med. Klaus-Dieter

Zastrow, Hohenstein Institute, 2010, Bönnigheim.

Hohenstein Institute, Dokumentation: Branchenspezifische Bewertung der Nachhaltigkeit des

gewerblichen / industriellen waschens und internationales benchmarking, Hohenstein Institute,

2011, Bönnigheim.

ITP, Environmental Management for Hotels, ITP, 2008, London UK. Jensen, Jensen washroom

systems, webpage accessed December 2011: http://www.jensen-group.com/products/jensen-

cleantech.html

Mab Hostelero, A 4 star laundry in the hotel Can Picafort Palace (Mallorca – Spain), Mab

Hostelero, 2004, Spain.

Nordic Ecolabelling, Nordic Ecolabelling of Laundry detergents for professional use, Version

2.0 15 December 2009 – 31 December 2012, Nordic Ecolabelling, 2009, Norway.

Nordic Ecolabelling, Nordic Ecolabelling of Textile Services, Version 2.1 15 December 2009 –

31 December 2012, Nordic Ecolabelling, 2010, Norway.

P&G, Control and modernisation of washing machines, Proctor and Gamble, 2011,

http://www.pgprof.info/Control-of-washing-machines.html

US EPA, Alternative Disinfectants and Oxidants: Guidance Manual (EPA 815-R-99-014), US

EPA, 1999, Washington D.C.

Wientjens B.V., AquaMiser specification sheet, Wientjens B.V., 2010, Milsbeek NL.



IMPRINT This document is an extract from a Scientific and Policy report by the Joint Research Centre (JRC), the

European Commission’s science and knowledge service. The scientific output expressed does not imply a policy

position of the European Commission. Neither the European Commission nor any person acting on behalf of the

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How to cite this document

This best practice is an extract from the report Best Environmental Management Practice in the Tourism

Sector to be cited as: Styles D., Schönberger H., Galvez Martos J. L., Best Environmental Management

Practice in the Tourism Sector, EUR 26022 EN, doi:10.2788/33972.

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